The present invention relates to a noise reducing structure of slide-cam die.
A general structure of conventional slide-cam die is as shown in FIG. 7.
That is, to a base plate 116 of a lower die 101, a work positioning member 103 for positioning a work 102 is secured, and for piercing a side wall 102a of the work 102, a passive cam 104 which slides in the direction approaching to and parting from the side wall 102a is disposed. A piercing punch 105 is horizontally secured to a portion of the passive cam 104 facing the side wall 102a of the work 102. Numeral 106 designates a stripper plate, numeral 107 designates a cushion rubber and numeral 108 designates a die bush.
To the rear side of the passive cam 104, a heel 109 is secured and through which a rod 110 whose end is screwed into the rear surface of the passive cam 104 inserted, thereby the passive cam 104 is urged in a direction parting from the side wall 102a of the work 102 by a coil spring 111.
Meanwhile, to a base plate 122 of an upper die 121, an actuating cam 123 is secured at a position facing the passive cam 104 of the lower die 101.
Numeral 124 designates a stripper plate, and numeral 125 designates a cushion rubber.
When piercing the side wall 102a of the work 102 by the slide-cam die, the upper die 121 descends from a top dead point, and while the upper face of the work 102 is pressed by the stripper plate 124 and the actuating cam 123 is backed up by the heel 109, an inclined actuating face 123a of the actuating cam 123 is contacted to an inclined passive face 104a of the passive cam 104 to bring the punch 105 close to the side wall 102a of the work 102 for piercing. The completion time of piercing is a state of bottom dead point shown in the figure.
When the upper die 121 ascends after the completion of piercing, the passive cam 104 slides in a direction parting from the side wall 102a of the work 102 by an urging force of the coil spring 111.
Recently, noise generated at pressing has caused social problems. Noise is generated when punching metal sheets or at pressing by the cam type die, wherein the inclined actuating face of the actuating cam hits and drives the inclined passive face of the passive cam. Particularly, the cam type die is very noisy and it is said that 40% of the whole press shop noise is occupied by noise of the cam type die.
In the above-mentioned conventional example, an inclination angle .theta. of the inclined passive face 104a of the passive cam 104 and an inclination angle 8 of the inclined actuating face 123a of the actuating cam 123 are formed into a same angle, and a large inclined actuating face 123a area of the actuating cam 123 and a large inclined passive face 104a area of the passive cam 104 are totally contacted with each other instantaneously to generate large noise. Since the quiescent passive cam 104 is suddenly moved forcibly, the punch 105 and the stripper plate 106 installed on the passive cam 104 and the cushion rubber 107 starts to vibrate to cause noises.
In view of the above-mentioned circumstances, the present invention provides a noise-reducing structure of slide-cam die, wherein in the slide-cam die comprising, for reducing noise in the slide-cam die as much as possible, a passive cam having an inclined passive face of a fixed inclination angle .alpha., and an actuating cam having an inclined actuating face of the same inclination angle .alpha. as that of the inclined passive face of the passive cam, and contacting the inclined actuating face of the actuating cam to the inclined passive face of the passive cam to drive the actuating cam for pressing a work; a roller is disposed rotatably at the side of the passive cam, and a speed control cam plate having, at a location of the actuating cam facing the roller, a cam face having, at a position where an upper die contacts to the roller at the beginning of descending, a low-speed inclination angle .beta. which is larger than the inclination angle .alpha. of the inclined faces of the passive cam and the actuating cam and close to a right angle, and a succeeding medium-speed inclination angle .gamma. which is slightly larger than the inclination angle .alpha. of the inclined faces of the passive cam and the actuating cam is disposed such that, after the medium-speed inclination angle .gamma. of the cam plate has contacted to the roller, the inclined actuating face of the actuating cam and the inclined passive face of the passive cam are brought in contact with each other to shift the passive cam to the low, medium and pressing speeds continuously for pressing.
The present invention is that, since the roller is disposed rotatably at the side of the passive cam, and a speed control cam plate having, at a location of the actuating cam facing the roller, a cam face having, at a position where an upper die contacts to the roller at the beginning of descending, a low-speed inclination angle .beta. which is larger than the inclination angle .alpha. of the inclined faces of the passive cam and the actuating cam and close to a right angle, and a succeeding medium-speed inclination angle .gamma. which is slightly larger than the inclination angle .alpha. of the inclined faces of the passive cam and the actuating cam is disposed such that, after the medium-speed inclination angle .gamma. of the cam plate has contacted to the roller, the inclined actuating face of the actuating cam contacts to the inclined passive face of the passive cam for pressing work, noise is reduced remarkably.